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“导数定义应用”练习题

“导数定义应用”练习题

作者: 7300T | 来源:发表于2019-03-17 19:44 被阅读78次

    已知f^{\prime}\left(x_{0}\right)=a求下列极限:
    1.\lim _{\Delta x \rightarrow 0} \frac{f\left(x_{0}+\Delta x\right)-f\left(x_{0}-\Delta x\right)}{\Delta x}

    1. \lim _{h \rightarrow 0} \frac{f\left(x_{0}+h^{2}\right)-f\left(x_{0}\right)}{h}

    解:

    \lim _{\Delta x \rightarrow 0} \frac{f\left(x_{0}+\Delta x\right)-f\left(x_{0}-\Delta x\right)}{\Delta x}

    =\lim _{\Delta x \rightarrow 0} \frac{\left[f\left(x_{0}+\Delta x\right)-f\left(x_{0}\right)\right]+\left[f\left(x_{0}\right)-f\left(x_{0}-\Delta x\right)\right]}{\Delta x}

    =\lim _{\Delta x \rightarrow 0} \frac{f\left(x_{0}+\Delta x\right)-f\left(x_{0}\right)}{\Delta x}+\lim _{-\Delta r \rightarrow 0} \frac{f\left(x_{0}-\Delta x\right)-f\left(x_{0}\right)}{-\Delta x}

    =2 f^{\prime}\left(x_{0}\right)
    =2 a

    \lim _{h \rightarrow 0} \frac{f\left(x_{0}+h^{2}\right)-f\left(x_{0}\right)}{h}

    =\lim _{h \rightarrow 0}\left[\frac{f\left(x_{0}+h^{2}\right)-f\left(x_{0}\right)}{h^{2}} \cdot h\right]

    =\lim _{h \rightarrow 0} \frac{f\left(x_{0}+h^{2}\right)-f\left(x_{0}\right)}{h^{2}} \cdot \lim _{h \rightarrow 0} h

    =a \cdot 0

    =0

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